Impact of climate change on Antarctic krill

Abstract

International audienceAntarctic krill Euphausia superba (hereafter `krill') occur in regions undergoing rapid environmental change, particularly loss of winter sea ice. During recent years, harvesting of krill has in creased, possibly enhancing stress on krill and Antarctic ecosystems. Here we review the overall impact of climate change on krill and Antarctic ecosystems, discuss implications for an ecosystem-based fisheries management approach and identify critical knowledge gaps. Sea ice decline, ocean warming and other environmental stressors act in concert to modify the abundance, distribution and life cycle of krill. Although some of these changes can have positive effects on krill, their cumulative impact is most likely negative. Recruitment, driven largely by the winter survival of larval krill, is probably the population parameter most susceptible to climate change. Predicting changes to krill populations is urgent, because they will seriously impact Antarctic ecosystems. Such predictions, however, are complicated by an intense inter-annual variability in recruitment success and krill abundance. To improve the responsiveness of the ecosystem-based management approach adopted by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), critical knowledge gaps need to be filled. In addition to a better understanding of the factors influencing recruitment, management will require a better understanding of the resilience and the genetic plasticity of krill life stages, and a quantitative understanding of under-ice and benthic habitat use. Current precautionary management measures of CCAMLR should be maintained until a better understanding of these processes has been achieved. [GRAPHICS]

Introduction to the special issue on the Life in Antarctica: Boundaries and Gradients in a Changing Environment (XIth SCAR Biology Symposium)

“…As a consequence, sea ice extent has been reduced in this region Fan et al 2014). Such changes have directly affected the food webs and declines of some organisms such as krill have been reported (Atkinson et al 2004;Flores et al 2012), while other organisms such as salps have increased their numbers (Atkinson et al 2004). In other Antarctic regions such as the Ross Sea, the scenario is quite different with an increase in the sea-ice extent (Fan et al 2014) and a decrease in the number of the ice-free days (Stammerjohn et al 2012), while also producing environmental effects in this region affecting the food web.…”

“…The southward displacement of the polar front may also alter the Earth's climate, modify community composition of plankton (Flores et al 2012;Wang et al 2014) and benthos (Thatje et al 2005a) and facilitate the intrusion of non-local species from more northern regions, which is also taking place due to the growing tourism in the islands off the Antarctic Peninsula (Frenot et al 2005).…”

Southern Ocean Phytoplankton in a Changing Climate

“…These bottom ice algal communities are an essential food source for zooplankton over winter (Brierley andreferences therein, Jia et al, 2016), when phytoplankton biomass in the waters beneath the sea ice are very low due to light limitation (Perrin et al, 1987;Legendre et al, 1992;Robins et al, 1995). For example, the phenology of the Antarctic krill, Euphausia superba, a keystone organism in SO food webs, is integrally liked to sea ice and seasonality, largely due to its being a refuge and source of algal nutrition over winter (Kawaguchi and Satake, 1994;Daly, 1998;Atkinson et al, 2004;Smetacek and Nicol, 2005;Quetin and Ross, 2009) and is associated with the ice at all stages of its life cycle (Flores et al, 2012 and references therein). Thus, changes in the timing and/or extent of sea ice cover are likely to have major implications for the Antarctic food web (see below, Quetin and Ross, 2009).…”

From strategic ambiguity to technical reference points in the Antarctic krill fishery: the worst journey in the world?

“…Any interpretation of the principle must be in the context of a changing ecosystem. The Southern Ocean ecosystem is changing in response to two centuries of largely unregulated harvesting, including the removal of up to 84% of baleen whale biomass (Laws 1977;Hill et al 2006), and to the changing climate (Flores et al 2012). Translating the reversibility principle into an objective with a relative reference point is a pragmatic approach to managing a single human activity (fishing) in this context.…”